Weird Fuel Gauge Problem

Rechecked my wiring again, every last bit. same problem no matter what. Soon as the fog light switch is hit, the fuel light goes down. Here is the strange part. So I have 2 separate sets of fogs wired separately on 2 separate OEM switches. One pair (35W HID) when turned on only makes the gauge go down a bit. When I turn the other set on (50W HID) makes the gauge go down to empty. Again new alternator in. Battery tests fine from what I can see. Over 14V when the truck is running, around 13+ when just parked and off. I am considering getting a new Battery next just incase it may be that but I'm just not sure anymore. Any other ideas?
 
Ok so MY PROBLEM HAS BEEN SOLVED!!!!! I was able to take all my connections apart at the lights themselves. I moved my grounds directly to the battery and amazingly my gas gage works perfectly with the fogs on. Thanks to all those with suggestions.
 
[MENTION=94888]EatonKyleH[/MENTION] Do you know if the mileage is stored somewhere else other than the cluster? I'm wondering if it's just easier to buy a 01-02 gauge cluster and swap it. But if the odo will be wrong then not gonna do it.
 
[MENTION=94888]EatonKyleH[/MENTION] Do you know if the mileage is stored somewhere else other than the cluster? I'm wondering if it's just easier to buy a 01-02 gauge cluster and swap it. But if the odo will be wrong then not gonna do it.

Hey man,
So switching over to a 01-02 cluster won't do you much good because the mileage is stored in the Number 3 circuit plate on your 99 which even if you transfer over the circuit plate to the new cluster it is the main piece that was updated to solve the gauge problems.... so you'd be swapping a faulty piece into new cluster to retain the mileage but also then swapping your main problem with it as well. Follow me?

Now for the solution... although it kinds sucks.

For your 99 (given it falls in the specific VIN range) you need to fill out the "Digital Odometer Order Form" and they will send you the updated circuit plate with the mileage you specify. Keep in mind that completion of the TSB also includes an updated gauge sender and longer suction tube so its far from plug and play.

I'll PM you the order form and TSBs spelled out with VIN ranges, part numbers, calibration, and so on so you can look through the process and decide if it is something you want to take on.

Sometimes Toyota does not like to sell programmed odometer plates to the public because of odometer fraud concerns yada yada.
If you find that to be the case PM me and I'd be glad to submit your form and ship it to you.

Let me know if you have any other questions I tried to cover everything I could think of lol.
 
I think [MENTION=25058]ChildrenOfBodom[/MENTION] had this issue a while back. He's got a video on his youtube channel showing it. I think it had something to do with the wiring and polarity of the fog lights being backwards. Let me try to find the video. Hopefully he'll chime in on this.
 
Yup I watched that vid and it sparked me into rechecking all my connections. I am rather stumped as to why the ground was not sufficient seeing the location was solid, but either way I'm glad to have this one behind me.
 
My 96 has gas guage issues as well although nothing to do with fog lights being turned off/on.

[MENTION=94888]EatonKyleH[/MENTION] there is nothing for those with a 96-98?
 
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My 96 has gas guage issues as well although nothing to do with fog lights being turned off/on.

[MENTION=94888]EatonKyleH[/MENTION] there is nothing for those for a 96-98?

Nope, the 96-98 gauge set up is a whole different story than the 99-2000. I can send you testing procedures for both the gauge and the sender though if you like.
 
[MENTION=94888]EatonKyleH[/MENTION] - would you mind providing them to me as well?

I have a 96 and the gauge is worthless. It will be full and show 3/4 then drop to E for a long time.

thanks
junr
 
[MENTION=94888]EatonKyleH[/MENTION] - would you mind providing them to me as well?

I have a 96 and the gauge is worthless. It will be full and show 3/4 then drop to E for a long time.

thanks
junr

Sure, PM me your email address and I'll send them over to ya.
 
[MENTION=94888]EatonKyleH[/MENTION] - would you mind providing them to me as well?

I have a 96 and the gauge is worthless. It will be full and show 3/4 then drop to E for a long time.

thanks
junr

Same kind of thing here too. Been dealing with it for 2 years although it has gotten better over time but still not the most reliable after I get below half a tank.
 
Mine just went totally wacky today!!

I think we should get some petitions going. The gauge on my '99 is all out of whack too. It will always read full when completely full but will never go before right above half a tank. I've been using my trip. for the past 6 or so months now. Very annoying.

I've had the same problem (fuel gauge only dropping to just above half full, for about the time time as you. Forgot about it one time, and ended up running out of gas about 5 miles from the nearest town. Thankful for the roadside assistance rider on my insurance policy!!

So I've been keeping a really close eye on the trip meter to make sure I don't go over 300 miles between fill ups - and there's usually 2 to 3 gallons left in the tank. This morning, however, something totally new happened. I started it up, and all was well until I put it in gear - and the fuel gauge needle dropped to below empty, and the gas pump idiot light started flashing like crazy. I had just filled up the night before and had a grand total of 4.3 miles on the trip meter, so I know I wasn't out of fuel. I stopped, shut the car off, then restarted - needle on the gauge went right to the top of the full mark, but as soon as I put it in gear - back to the bottom with the flashing light again!! I've got over 241,000 on it - and was hoping not to have to spend a lot of money on my way to 250,000, so I think I'll just watch the trip meter, and put some black electrical tape over the idiot light.......
 
This just happened 2 days ago to my 99.. Did anyone figure out what the relationship between the fog lights and fuel gauge doing that wacky drop and blink..? I did have to change one of my fog light bulbs on Sunday just before this happened but I drove it for 3 and 1/2 hours Sunday and a couple more on Munday before it actually first happened.. None of it makes sense to me that my fog lights have something to do with my fuel gauge...
 
I have been chasing this problem for about 5 years. As best I can figure he T4R wiring is somewhat fragile and spicing or tapping into wires upsets the system balance. On page 1 of the this thread The DURK opines that taking power at the battery and routing it through a relay may be a fix.

BTW, my problem started when I added a trailer hitch and Uhaul tapped into the harness with a third party "plug and play". come warm weather I will disconnect the trailer lights and see if it changes anything. "The DURK" if you are still on the net. please let us know.
 

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